Event parameter is visible in GA4 not accessable

Server Google Analytics
1

I’m tracking an A/B test using the stape data tag and a custom event called experience_impression.
Each time the experiment loads, the site sends this event to GA4 along with a parameter that contains the assigned variant (A/B/etc.).

I can see the event in GA4, and I can see that the variant parameter is recorded correctly. So the data is being collected, and the event + parameter both appear in real-time and in the Events report.

The Problem
I can’t use this variant parameter in any GA4 exploration.
When creating a custom segment for it it’s registered but can’t show any data, and funnels or free-form explorations show no data when I try to filter or break down by the variant.

GA4 simply won’t let me work with the data anywhere inside Explorations, even though the raw event data clearly exists.

So:

  • The event is firing
  • The parameter is attached
  • GA4 shows all of it in the Events report
  • But Explorations can’t use it at all

Has anyone run into this where an event parameter is visible in GA4 but completely unusable inside Explorations?

2

You need to register the custom parameter in “custom dimensions” in GA4